1. Field of the Invention
The present invention relates to systems and methods for controlling fuel included within exhaust gases to facilitate regeneration of a particulate filter.
The present invention further relates to systems and methods to re-open ash filled channels in Diesel Particulate Filters by increasing the temperature within the Diesel Particulate Filter in response to an indication that one or more of the channels in the DFP are filled with Ash to sinter the ash in the channels, thereby reducing the volume of the ash to fraction of its unsintered volume to substantially re-open channels in DPFs.
The present invention further relates to systems and methods to re-open ash filled channels in DPFs by controlling the temperature in the DPF to exceed 700° C. to 1,000° C. in a controlled manner for a period of time sufficient to sinter any ash in the DPF to reduce the volume of such ash and re-open any plugged channels within the DPF. By controlling the temperature and time, it has been determined that the catalytic coating within the DPF is not significantly affected and that the ash is sintered into very small patches that are adhered to the walls of the DPF, thereby opening the channels and extending the life of the DPF.
2. Background Art
A particulate filter is a device for capturing particulates emitted in exhaust gases from a combustion engine. In some systems employing a particulate filter, it may be desired to oxidize or burn the captured particulates in a process commonly referred to as regeneration. The regeneration of the particulates is dependent on temperatures at the particulate filter, which may be influenced by exhaust gas fuel levels. In the past, it has been known to increase the temperature within the DPF to oxidize any particulate matter trapped therein and to permit the ash in the DPF to be effectively transported to the end of the channels to reduce the ash volume until the ash fills the channels within the DPF, thereby necessitating a replacement or cleaning of the DPF.
The temperature within the DPF has been increased by changing engine operation to increase the temperature of the exhaust gas, or by use of a fuel doser to introduce fuel into the exhaust stream to increase the temperature within the DPF. In the past, it has been a concern within the art that the temperature within the DPF cannot exceed about 450-650° C. because of the danger of uncontrolled oxidation of the particulate material trapped in the DPF, and further because temperatures in excess of this range may damage the catalytic coating with in the DPF, thereby reducing its effectiveness, assuming the DPF has been catalytically coated.
Accordingly regeneration efforts have been directed at a controlled oxidation of trapped diesel particulate material to reduce its volume and permit continued operation of the DPF. However, regeneration of the DPF does not remove the ash that eventually plugs the channels of the DPF, thereby necessitating replacement or cleaning of the DPF.
Accordingly, a need exists to control the increase in temperature of the DPF to 700° C. to 1,000° C. for a short period to sinter the ash within the DPF, further reducing its volume to a fraction of its unsintered form, thereby effectively re-opening ash plugged channels in the DPF and extending the life of the DPF. In addition, a need exists to control the increase in temperature to 700° C. to 1,000° C. for a controlled period of time in order to minimize the adverse affect the catalytic coating on the walls of the DPF, thereby effectively extending the life of the DPF.